Isotopic alteration of carbonate rocks during hydrothermal flow is common across a range of geological settings, can be used to identify areas of greater mineralization potential, and is a guide to mineral exploration. To understand potential controls on the variability of this isotopic alteration, we created a series of models to investigate parameter sensitivity. The resulting variograms for δ¹⁸O distribution closely matched the variograms for the initial porosity and demonstrate the importance of porosity in controlling isotopic variation. This result shows the utility of variograms for investigating the correlation between hydrologic parameters and isotopic distribution and vectoring toward ore deposits. The mass transfer variables between flowing and stagnant zones within the model were the strongest secondary control on isotopic alteration. The alteration of the carbonate rocks releases ¹⁸O, creating a pulse of enriched fluid that flows through the system. The isotopic variation of the solid phase decreases with distance from the inlet because of mixing and the increased size of the ¹⁸O-enriched pulse that travels through the system within the fluid phase. The isotopic pulse seen in the model matches isotopic records preserved in zoned calcites from the Upper Mississippi Valley. We also inferred from the model that when sampling isotopic systems, sample intervals taken from large intervals of core can reasonably be used to determine the average alteration but that characterizing the variation is sensitive to sample spacing and frequency.

热液流过程中碳酸盐岩的同位素蚀变在一系列地质环境中很常见，可用于识别具有更大矿化潜力的区域，并且是矿产勘探的指南。为了了解对这种同位素变化变异性的潜在控制，我们创建了一系列模型来研究参数敏感性。δ ¹⁸的结果变异函数O 分布与初始孔隙度的变异函数密切匹配，并证明了孔隙度在控制同位素变化中的重要性。该结果显示了变异函数在研究水文参数与同位素分布之间的相关性以及向矿床矢量化方面的效用。模型内流动区和停滞区之间的传质变量是对同位素变化最强的次要控制。碳酸盐岩的蚀变会释放¹⁸ O，从而产生流经系统的富集流体脉冲。由于混合和¹⁸在流体相内穿过系统的富氧脉冲。模型中看到的同位素脉冲与密西西比河上游地区方解石中保存的同位素记录相匹配。我们还从模型中推断，在对同位素系统进行采样时，可以合理地使用取自岩心大间隔的采样间隔来确定平均蚀变，但表征变化对采样间隔和频率敏感。